Lewis Hamilton headed team-mate Valtteri Bottas for Mercedes in second practice at the 70th Anniversary GP.
Hamilton was 0.176 seconds ahead of Bottas but on different tyres.
Mercedes were assessing which tyres might be most suitable for qualifying as teams struggled with durability in high temperatures at Silverstone.
Renault's Daniel Ricciardo was third, from Red Bull's Max Verstappen and Racing Point's Lance Stroll and Nico Hulkenberg.
The lifetime - or lack of it - of the tyres was the big focus of the day as teams came to grips with a softer tyre selection from Pirelli than at last weekend's British Grand Prix at the same track.
The tyres are all one grade softer this weekend, so last weekend's 'soft' tyre - which was very much not favoured - is the medium this weekend, and the 'hard' which was the preferred race tyre last weekend is not supplied this time.
- Second practice results
- Mercedes in stand-off with F1 over 2021
- Listen: 70th Anniversary Grand Prix preview
The tyre supplied as the 'soft' this weekend is the second softest of Pirelli's range, and it appears unsuited to the demands of Silverstone's high-speed sweeps on a summer's day with temperatures of 30C.
Hamilton's fastest time was set on medium tyres, while Bottas' was on a soft. Stroll and Hulkenberg also used the medium to set their fastest times.
Behind the Racing Points, Ferrari's Charles Leclerc was seventh quickest, ahead of the McLarens of Lando Norris and Carlos Sainz. George Russell was 16th in the Williams.
Leclerc's team-mate Sebastian Vettel was closer to the 22-year-old than he was on a bad weekend for the German last time out, but still 0.4secs back in 14th place. Vettel also suffered an engine failure towards the end of the session.
The day was dominated by off-track news.
Hulkenberg's role as stand-in for Sergio Perez, who has coronavirus, was confirmed only a couple of hours before the first session.
Following a series of protests from Renault, Racing Point were also found to have breached the regulations on designing their car and fined €400,000 and docked 15 points for illegally copying Mercedes' 2019 brake ducts.
And in the gap between the sessions, Mercedes F1 boss Toto Wolff revealed that the team were in a stand-off with the sport's bosses over the new contract they need to sign to race in 2021.